One of the major achievements of medical science over the last few centuries is an extension of life expectancy. Historically, almost all religions practices have valued long life. Some of the religions emphasize disengagement/detachment in the old age as frailty becomes inevitable. However, till recent times, researchers did not discuss much about how best to live long life. Over the years, there is an emphasis on not just having for long only but also having disease-free long life.

Fortunately, the life expectancy has also increased in India. Compared to life expectancy of 32 years at the time of independence, it was estimated to be 65 years for the year 2011. [1] Those aged >60 years formed 5.5% of the total population in 1951, which increased to 8.5% in 2011 and it is projected that by 2050, elderly will form 19% of the total population, with higher growth for those aged ≥80 years. [2],[3],[4] However, should we be happy with increase in life expectancy and proportion of elderly only or should we focus on aging healthily. Unfortunately, there is no focus on healthy aging in India. In this editorial, an attempt is made to understand the concept of successful aging and in the end an attempt is made to understand the relevance to India.

In the Western world, before 1980s, much of the discussion in relation to aging was on distinction between the pathological and nonpathological aging with focus on having or not having diseases or disabilities. The basic understanding was that those who were free from disease and disability, other age-related physical functions, and cognitive functions were normal, which was primarily determined by the genetic factors. [5] However, this concept was challenged, and one of the major concepts which have emerged over the last three decades or so is successful aging. In a landmark article, Rowe and Kahn [6] introduced the term successful aging and distinguished usual aging from "successful aging." They considered successful aging to include three main components, i.e., having low probability of disease and associated disability, high cognitive and physical functioning, and active engagement with life. [5] They further emphasized that successful aging does not merely involve the absence of disease or maintenance of functional capabilities, but requires combination of both along with active engagement with life. [5] Thus, although maintenance of functional capacities and low risk for disease are very important, their combination with active engagement is considered central for defining successful aging. On the basis of this definition, research started in this area, and many authors evaluated the model of Rowe and Kahn [6] and it was soon realized that very few older people fulfilled all the three components of successful aging. Further, some of the researchers criticized the concept that the model of Rowe and Kahe [6] and suggested that the model downplayed the importance of genetics and species-determined deterioration of late life, did not lay emphasis on spirituality [7] and subjective well-being. [8] Further, it was suggested that from a life-span developmental perspective, successful aging model failed to address losses, gains, and balance in later life. [9],[10]

Over the years, many researchers developed their own model for and described different components of successful aging. In fact, the concept was also referred differently, i.e. the various synonymous terms used include positive aging, active aging, aging well, healthy aging, optimum aging, productive aging, vital aging, and robust aging. [11] In recent decades, the most popular term in the United States has been successful aging and that in Europe has been active aging. [12] There is no universally accepted definition of successful aging. In fact, in a review of quantitative studies on successful aging in 2006, it was reported that there were at least 29 different definitions of the concept and most of these definitions focused on physical health. [13] The various components considered by these definitions include disability/physical functioning (26 definitions), cognitive functioning (13 definitions), life satisfaction/well-being (9 definitions), social/productive engagement (8 definitions), presence of illness (6 definitions), longevity (4 definitions), self-rated health (3 definitions), personality (2 definitions), environment/finances (2 definitions), and self-rated successful aging (2 definitions). Based on the definition, the prevalence of successful agers in different studies ranged from 0.4% to 95%. [13] In a systematic review of lay perspectives of successful ageing, three components, i.e., biomedical (physical functioning/disability, cognitive functioning/disability, affective status, presence/probability of disease, mental health, and longevity), psychosocial (personal resources, engagement, life satisfaction/well-being, support system, and independence/autonomy), and extrinsic factors (environment, finances-income, and financial security) were identified. The authors reported that from lay perspective psychosocial components, notably engagement (e.g., social engagement), and personal resources (e.g., attitude) are the important components of successful aging, more often than "physiological" components, such as longevity or physical functioning. [14]

The World Health Organization [15] uses the term active aging and defines it as "the process of optimizing opportunities for health, participation, and security in order to enhance quality of life as people age" allowing people to "realize their potential for physical, social and mental well-being throughout the life course". The term "active" was further defined as "continuing participation in social, economic, cultural, spiritual and civic affairs, not just the ability to be physically active or to participate in the labour force." [16] Hence, it can be said that successful aging is a multidimensional concept, with the basic goal of disease and disability-free life with high physical and cognitive function and active engagement with life in old age.

Studies have evaluated the various predictors of successful aging. These predictors can be broadly understood as socio-demographic variables (men as opposed to women), higher income, better education, and younger), lifestyle-related variables (nonsmokers, regular use of wine or beer (but not other hard drinks, regular physical exercises), physical health (strength and lung capacity, body mass) and psychological variables (intelligence), personality variables (positive appraisal of physical fitness, lack of neuroticism, positive emotional balance, extraversion, and self-efficacy), and social variables (helping others, family network, and receiving help). In their review, Depp and Jeste [13] reported that the most frequent significant correlates of the various definitions of successful aging were age (young-old), nonsmoking, and absence of disability, arthritis, and diabetes. Further, they found moderate level of support for greater physical activity, more social contacts, better self-rated health, absence of depression and cognitive impairment, and fewer medical conditions.

Over the years, based on the current level of understanding of the concept, researchers have started discussing about the promotion of healthy aging. There are no defined and standard outcome measures on which the strategies for the effectiveness of successful aging can be evaluated. [17] Harmell etal. [17] tried to operationalize "successful aging strategy" as an intervention that can acts on a potentially modifiable variable with intent to enhance or promote the functioning of elderly subjects who can be considered to be aging normally. The various interventions have been considered to promote healthy aging [Table 1]. [17],[18],[19],[20],[21] Among the various activities, physical activity has been shown to be associated with lower cognitive decline and/or better cognitive functioning. [22] Similarly, activities which enhance cognitive stimulation, such as crossword puzzle participation, have been shown to delay future cognitive decline, even in patients with dementia. [23] Studies have also evaluated the role of yoga and meditation have been shown to be associated with better sleep quality, less of fatigue, general well-being, less of depression, anxiety and stress, and better cognitive performance. [24],[25]

Unfortunately, at present, in India, there is no focus on successful aging at the level of the community and among clinicians too. The basic focus is on the management of communicable and chronic noncommunicable diseases. There is scarcity of data in terms of factors associated with successful aging. In India, significant proportions of elderly live in rural India and belong to below the poverty line. There is limited data on variables associated with successful aging from India. [26] Some of the data suggest that poverty, social inferiority, social isolation, physical weakness, vulnerability, powerlessness, and humiliation are the major obstacles to successful aging in rural India. [27],[28] There is a need to assess the determinants of successful aging in the Indian context. There is also a need to determine the factors which can be used to understand the concept of successful aging in the Indian context.

Severe mental disorders are known to be associated with premature mortality. [29] Patients with severe mental disorders also have high prevalence of cardiovascular diseases, comorbid substance use/dependence including tobacco dependence, lower physical activity, poor cognitive functioning, disability, and poor quality of life. [17],[30],[31] Some of the authors have proposed the models of progressive courses of illness over the lifetime, such as "neuroprogression" model for bipolar disorder, which try to integrate the current level of knowledge about the course of the disease and brain aging. [17] This suggests that there is an overlap between the factors influencing aging and those seen in patients with psychiatric illnesses. Hence, it is important for the mental health professionals to recognize these adverse factors and encourage their patients to indulge in healthy behaviors so that they have successful aging without much morbidity. Further, there is a need to raise the issue of successful or active aging with the policy makers so that mass scale strategies can be devised for active aging.

Census of India, 2011. Government of India. Ministry of Home Affairs. Office of Registrar General and Census Commissioner, India. Available from: http://www.censusindia.gov.in/. [Last accessed on 2016 Oct 19].

United Nations Population Division (UN). World Population Prospects: The 2010 Revision. New York: United Nations, 2011. Available from: http://www.esa.un.org/unpd/wpp/index.htm. [Last accessed on 2016 Oct 19].